NatHERS Foundations
A NatHERS assessment reviews the thermal performance of a residential design before it is built. It helps show how the home is expected to perform in its climate and whether the design is on track for the required star rating.
A NatHERS assessment is a thermal performance assessment for Australian homes. An assessor reviews the proposed design, models the home using accredited NatHERS software and produces a star rating that reflects the home’s predicted heating and cooling needs. The assessment considers the building fabric, orientation, glazing, insulation, shading, construction materials and local climate.
A NatHERS assessment begins with the project documentation. The assessor reviews the drawings and building information to understand the home’s layout, orientation, construction type and thermal design features.
The home is then modelled in NatHERS accredited software. This modelling process estimates how much heating and cooling may be required to keep the home comfortable across the year, based on the design and local climate conditions.
The result is a NatHERS thermal star rating out of 10. A higher rating generally means the home is expected to need less heating and cooling to remain comfortable. The assessment may also identify where design changes could improve performance before the project is finalised.
A NatHERS assessment relies on clear design information. The more complete the documentation is, the easier it is to model the home accurately and avoid assumptions that may affect the result.
• Floor plans, elevations and sections
• Site orientation and project location
• Wall, roof, ceiling and floor construction details
• Insulation levels and proposed building fabric specifications
• Window and door sizes, frame types and glazing performance
• Eaves, awnings, balconies, pergolas and other shading elements
• Roof colour, floor type and other details that may affect thermal performance
If some information is missing, the assessor may need to request clarification or use conservative assumptions. This is why NatHERS is best handled while the design team can still provide detail and respond to performance recommendations.
A NatHERS assessment matters because thermal performance is shaped by design decisions. A home’s comfort is not determined by one feature alone. It is affected by the relationship between layout, orientation, glazing, insulation, shading, thermal mass and local climate.
When the assessment is completed early enough, it can help identify whether the design is likely to meet the required performance level. If the rating is lower than expected, there may still be time to adjust specifications or improve design features before approvals, construction documentation or procurement progress too far.
This makes the assessment useful for more than compliance. It can also support better comfort outcomes and help the project team make more informed decisions about the building fabric.
For many new residential projects, NatHERS forms part of the energy efficiency compliance pathway. It is commonly used to demonstrate the thermal performance of new homes, townhouses and apartments in relation to the applicable residential energy requirements.
In NSW, NatHERS modelling often sits alongside BASIX. For projects under current residential energy requirements, the thermal star rating may also connect with Whole of Home considerations, which look beyond the building fabric to major energy use, generation and systems.
The key point is that NatHERS focuses on the thermal performance of the home itself. It helps answer a specific question: how well is the design expected to moderate heat and cold before relying on mechanical heating or cooling?
A NatHERS assessment can be completed once there is enough design information to model the home. However, waiting until the design is completely locked in can make improvements harder.
For smoother outcomes, it is often better to consider NatHERS before finalising glazing, insulation, roof colour, shading and construction specifications.
Australian homes are assessed in relation to local climate. A design response that works well in one climate zone may not suit another. For example, the balance between solar access, shading, ventilation, insulation and glazing performance can change depending on whether the home is in a cooler, temperate, hot dry or humid climate.
This is why a NatHERS assessment should not be treated as a generic checkbox. The same star rating target can require different design strategies depending on the location, orientation and construction approach.
Good outcomes usually come from coordinating the assessment with the broader design process. Early attention to window placement, insulation continuity, shading, roof design and material selections can make the compliance pathway clearer and the home more comfortable to live in.
Certified Energy provides NatHERS assessments for Australian residential projects, including new homes, townhouses and multi residential developments. Our team reviews the project documentation, models the proposed design and helps identify practical pathways toward the required thermal performance outcome.
Where relevant, we can also help connect the NatHERS assessment with related residential compliance requirements, including BASIX, 7 Star Rating, 6 Star NatHERS and Whole of Home.
For a broader explanation of how NatHERS works across residential design and compliance, visit our NatHERS Knowledge Hub.
A NatHERS assessment is a residential thermal performance assessment. It models a home design and calculates a star rating that reflects the predicted heating and cooling needs of the home.
What does a NatHERS assessor look at?A NatHERS assessor reviews the design, orientation, construction materials, insulation, glazing, shading and other building fabric details that affect thermal performance.
Is a NatHERS assessment only about compliance?No. Compliance is an important reason for completing a NatHERS assessment, but the assessment can also help the design team understand thermal performance, comfort and where the building fabric may need improvement.
When should a NatHERS assessment be done?A NatHERS assessment is best considered before the design is finalised. This gives the project team more flexibility to adjust glazing, insulation, shading or other details if the rating needs to improve.
Does a NatHERS assessment include Whole of Home?The NatHERS thermal star rating focuses on the building fabric and heating and cooling needs. Whole of Home looks more broadly at major energy use and generation, including items such as hot water, appliances, solar and batteries where applicable.